Weathering Effects on the Engineering Properties of Sydney (Yellow Block) Sandstone when used as a Building Material

Sydney (Yellow Block) Sandstone is the primary building material used in many nineteenth century buildings in Sydney, Australia. As a natural material, it is subject to deterioration in the salty environment and in extreme cases will need to be removed and replaced. Two cornice pieces have been removed from State Heritage Registered, the Australian Museum due to evidence of visual decay patterns including surface degradation, slight sanding, granular disintegration, contour scaling and flaking, pitting, discoloration, soiling, alga growth and there are missing parts. Stone samples removed from within these building elements were tested for their engineering properties after over 100 years of natural exposure. It was found that the stone has become weaker, softer, less durable, and has an increased capacity to absorb water. The stone was found to be more susceptible to attack from sodium sulfate ingress as opposed to sodium chloride, which would have contributed to the weathering effects noted on the stone. The degree of exposure experienced by each building element was also found to be a factor in the loss of stone quality.